A latest examine has discovered that tunnel oxide passivated contact (TOPCon) photo voltaic modules, regardless of their rising recognition, present three distinct failure modes that aren’t current in conventional passivated emitter and rear cell (PERC) modules. This analysis was carried out by a staff on the College of New South Wales, Australia, and printed within the journal Photo voltaic Vitality Supplies & Photo voltaic Cells. The examine in contrast the reliability of TOPCon and PERC photo voltaic modules underneath damp warmth testing situations, which simulate extended publicity to excessive humidity and temperature, generally skilled within the subject.
The researchers used totally different supplies within the building of each PERC and TOPCon modules, resembling polyolefin elastomer (POE) and ethyl-vinyl acetate (EVA), together with numerous polymer backsheets. Whereas PERC modules remained steady underneath testing, with solely a minimal energy lack of about 1 to 2 p.c, the TOPCon modules confirmed considerably extra degradation. The TOPCon modules skilled a decline in energy output starting from 4 to as a lot as 65 p.c after 1000 hours of damp warmth publicity. This efficiency drop occurred even when POE, an encapsulant identified for its low water vapor transmission price, was used.
Three kinds of failures had been recognized within the TOPCon modules. The primary failure mode is point-localized, showing as darkish spots in electroluminescence imaging. The second failure happens at or across the connection factors between the ribbon wires and busbars, whereas the third kind includes widespread failure throughout all the module space. These points are thought to outcome from electrochemical reactions brought on by the presence of moisture, cell metallization, ribbon wires, soldering flux, and different contaminants. Contaminants resembling sodium and chlorine, typically launched throughout the manufacturing course of or from dealing with, are suspected to play a serious position in accelerating the degradation of TOPCon cells.
The findings present that the TOPCon know-how, though thought of to be the way forward for photo voltaic cell design, is extremely delicate to humidity and contaminants. The examine means that the kind of POE used for encapsulation can have a big impression on the reliability of TOPCon modules. Particularly, sure POE sorts had been discovered to negatively have an effect on TOPCon efficiency, resulting in critical energy losses.
Additional analysis is required to raised perceive the results of various encapsulation supplies and the way they work together with the parts of TOPCon cells. The authors stress the significance of strict high quality management throughout manufacturing and dealing with processes to forestall contamination. Additionally they spotlight the necessity for intensive testing of encapsulants and module designs earlier than large-scale deployment of TOPCon know-how.
In distinction, PERC modules demonstrated a lot better stability and decrease susceptibility to damp warmth situations. Their energy output declined minimally, whatever the supplies used within the module building. This means that PERC know-how, though older, should supply benefits by way of sturdiness in sure environmental situations.
The researchers conclude that whereas TOPCon know-how holds promise for greater effectivity in solar energy era, extra work is required to make sure its long-term reliability. Builders and producers are inspired to train warning when deciding on supplies and to prioritize enhancing the design and safety of TOPCon photo voltaic modules. With out addressing these failure modes, the advantages of TOPCon could also be undermined by its potential for early degradation in real-world situations.
